Author Topic: VEMS help adding aux air valve and ALS trigger switch  (Read 6633 times)

Offline 88a5tq

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VEMS help adding aux air valve and ALS trigger switch
« on: April 30, 2018, 02:56:04 pm »
Hello everyone.
I've been searching the VEMS forums (and no, not Versatile Exercise Mine System :) ) for information concerning adding two features to my PnP audi 3B ecu. I have not found what I'm looking for unfortunately.

Is there a resource that explains what is needed to add an air valve to be controlled by the ecu as well as adding a switch for input? I'd like to find the info myself before putting together a plan and checking it with the VEMS forum for validity. These 2 additions will be for adding ALS during overrun conditions.

I prefer finding the info myself and compiling the plan first, and have it reviewed.

It was relayed to me by a very helpful source that I could accomplish a "pull-up" on one of my mcp chip inputs externally in order to switch it to ground for ALS activation. I have not found any further information on this yet.

"you can do it external to the ecu if you want.

wire a 2k ohm (or so, the value isn't super critical, just more than 1k and less than 10) between any 5v source (like the tps or the cps 5v supply line) and your analog input channel."

In my mind's eye I picture this as a simple circuit which takes the +5v supply from my oem 3b harness and grounds it directly to the mcp chip channel 1 in the VEMS aux harness, with a resistor in between. But in the case of my channel 2 for LC activation, it's switched from the VEMS to ground, through the clutch switch.

So with that in mind, do I take the formerly mentioned +5v supply wire and twist it to the same side as the mcp channel 1 wire of a butt connector and wire the other side of the connector to the ALS switch which will go to chassis ground? I don't have Photobucket 3rd party posting so I can't include my cheat sheet or circuit sketch. Someone on the VEMS FB group suggested wiring it like the efiexpress sketch for the LC circuit except replacing the 12v supply with the 5v tps supply I'll patch into on the OEM harness. The discussion has started on the FB group and the pictures are there as well.

Now that is for the switch-side of my overall project so how do I incorporate a VEMS-controled aux air valve to complete the ALS installation?

Again, I would rather find the source you all refer to so I can sketch it completely and have it reviewed later.

Please help if you can, thanks. I feel this particular information should be easily accessible to VEMS ecu owners because of how important it is to functionality expansion.

This is a test.

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Offline gunni

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #1 on: May 02, 2018, 07:16:04 pm »
For the ALS switch,  you have described exactly how to do it.

Gnd - Switch ON - ECU analog in with a pullup shows 0v
Gnd - switch off - ECU analog in with a pullup shows 5v

In the ALS settings there is a Throttle kicker solenoid config section

Set to enabled
Select the output you have wired the solenoid or a relay to.
Select if VEMS should keep it on always until EGT or the time period has elapsed.

Offline 88a5tq

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #2 on: May 02, 2018, 07:22:04 pm »
Thank you! As soon as the trans is reassembled I will proceed with this lol. Much appreciated.
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Offline 88a5tq

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #3 on: May 23, 2018, 01:27:39 am »
https://flic.kr/p/KhZ1mf

I'm trying to include my cheat sheet above..

So just to be clear this is the correct wiring as listed in my OP?

"takes the +5v supply from my oem 3b harness and grounds it directly to the mcp chip channel 1 in the VEMS aux harness, with a resistor in between"

And that would appear like so:

https://flic.kr/p/264hmST

Sorry, I'm 100% unable to attach photos or display them in my posts.

Again, thank you so much Gunni!
« Last Edit: May 23, 2018, 01:42:06 am by 88a5tq »
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Offline gunni

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #4 on: May 23, 2018, 07:51:45 pm »
hi, that looks right, just remember that  you might not need the 5v pullup IF the channel is already 5v in the ecu with nothing connected to it.

Offline 88a5tq

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #5 on: May 23, 2018, 09:38:24 pm »
Oh nice! Thank you very much. I know there's high risks of damage to the circuitry if I screw that up so I'm sure you understand my need to draw it and have it confirmed. Happy motoring!
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Offline 88a5tq

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #6 on: May 23, 2018, 09:41:59 pm »
Cheat sheet for redundancy:
https://flic.kr/p/KhZ1mf

Btw, does it appear to you that I have no channels left spare once I use that last channel (channel one)? I have channel 2 for LC clutch switch already. The other stuff looks like it's all mostly being used for the coil-on-plug setup for the 3b engine. I need one last unused channel to control the ALS kicker valve.
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Offline gunni

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #7 on: May 30, 2018, 07:57:15 pm »
Unless there are some other unused analogs that will be it.

Offline 88a5tq

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Re: VEMS help adding aux air valve and ALS trigger switch
« Reply #8 on: June 30, 2018, 05:27:47 pm »
Thank you for all your help and advice! This mcp input switching on channel one is working perfectly.

I have decided to try ALS through config switching using this newly wired mcp channel. On table B I have ALS as always on and the IAC supplied with 90%DC as a test. I am getting a 4k rpm idle using the stock (newer Bosh) valve in conjunction with the mid-1k rpm fuel-cut set to 10k rpm to effectively disable it as it was causing surging.

Today it's super hot out but I'm going to go back out to test ALS with much more fuel enrichment than before. Idle at 4k and 20% enrichment is only getting me about stoichiometric but I assume it needs to be much more enriched. Also my earliest tests didn't show ALS as even being enabled in the top status bar. I will see how it goes today.
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